The present invention relates generally to a method for altering the luminescence of semiconductors and, more particularly, to a method for producing light emitting semiconductor (LES) devices having regions of varying luminescence.
Integrated circuits are becoming increasingly smaller and more densely occupied resulting in bottlenecks in the transmission of data along electrical pathways. While the use of optical pathways could greatly enhance the flow of data, finding a material which is both compatible with integrated circuit materials and one which could be used as an optical pathway as well as for new types of displays, signal processors and optical computers has long been a desire of the microelectronics industry. In particular, the use of silicon for optical pathways would integrate far more easily and cheaply with standard silicon-based semiconductor devices than current practices of adapting other materials with such devices.
Until recently, attempts to use silicon as the material for both the optical and electronic circuits of an integrated circuit have been littered with failure. With the recent revelations of S. Furukawa, et al in "Quantum size effects on the optical band gap of microcrystalline Si:H" Phys.Rev. B Vol. 38, 5726 (1988) and in "Three-dimensional quantum well effects in ultra fine silicon particles" Jpn. J. Appl. Phys. 27, L2207 (1988); H. Takagi, et al in "Quantum size effects on photoluminescence in ultra fine Si particles" Appl. Phys. Lett. 56, 2379 (1990); and L. T. Canham, in "Silicon quantum wire array fabrication by electrochemical and chemical dissolution of wafers" Appl. Phys. Lett. 57, 1046 (1990), methods for fabricating light emitting semiconductor (LES) devices from silicon have been developed. The essence of such methods is to produce a porous silicon structure on a silicon substrate wherein the porous structure comprises nanometer sized wires of silicon or a sponge-like structure of silicon. Both photoluminescence and electroluminescence have been demonstrated in such porous silicon structures. Nevertheless, for such porous silicon structures to be used as an optical pathway as well as for new types of displays, signal processors and optical computers, a need still exists to produce regions of the LES having specified intensities of luminescence.